1. Field
Example embodiments relate to a separation membrane, and more particularly, to a graphene-containing separation membrane and/or a sea-water desalination and/or gas separation apparatus including the same.
2. Description of the Related Art
Example embodiments relate to a graphene-containing separation membrane, a method of preparing the same, and/or a gas/liquid separation apparatus employing the graphene-containing separation membrane, and for example, to a graphene-containing separation membrane, a method of preparing the graphene-containing separation membrane, and/or a gas/liquid separation apparatus using the graphene-containing separation membrane.
Gas separation processes include membrane separation processes, pressure swing adsorption (PSA) processes, cryogenic processes, and the like. PSA and cryogenic processes have been developed, and are currently used. Gas separation using membrane separation is relatively short in history.
In 1977, Monsanto Co. developed a gas separation process using a polymer membrane and this led to a gas separation module marketed under the product name PRISM. Air Products currently markets gas separation products using polymer membranes under the product name PRISM®.
Gas separation membranes may use organic polymers, including polysulfone, polycarbonate, polypyrrolones, polyarylate, cellulose acetate, polyimide, and the like. Although some polymer materials show high separation efficiency with respect to specific gas mixtures, many polymer materials have limited applications because of high costs and manufacturing difficulties. The manufacturing difficulties may include difficulties related to manufacturing separation membranes in the form of a planar thin film sheet or a hollow thread.
In general, natural and synthetic polymer gas separation membranes formed with a dense structure on a solid membrane (such as planar membrane, composite membrane, or hollow thread form) may exhibit high selectivity with respect to gas mixtures, and have been manufactured largely as an asymmetric membrane with a thin selective separation membrane on a porous support to increase a flow amount to pass per unit time.
However, polymer materials with commercially available performance in air separation (an oxygen permeability of 1 Barrer (1 Barrer=10-10 (cm3(STP) cm/cm2s cmHg) and an oxygen/nitrogen selectivity of 6.0 or greater) are considerably limited to a few in number. This is attributed to considerable restrictions in improving a polymer structure and a strong tradeoff between permeability and selectivity, which means a limit to the separation and permeability performance beyond upper limits. Furthermore, many existing polymer membrane materials are noticeably limited in permeability and separation characteristics.
Additionally, many existing polymer membrane materials decompose or age when exposed to high-pressure and high-temperature processes, or to gas mixtures including a hydrocarbon, aromatic hydrocarbons, and polar solvent for a long time, thereby leading to a markedly reduced initial membrane performance. Despite of high economical values of the gas separation process, these drawbacks have restricted the applications for many polymer membrane materials.
Therefore, polymer materials satisfying high permeability and selectivity requirements and the development of a novel gas separation membrane employing these materials is desired.